Android build instructions out of date

```sh
cd src/conformance
./gradlew clean && ./gradlew build
```
there is no folder conformance.

I found gradle in hello_xr but building it under arch linux currently fails with this exception for me:

`BUG! exception in phase 'semantic analysis' in source unit '_BuildScript_' Unsupported class file major version 65`

I try to build OpenXR for Meta Quests.

Start by checking the documented commands for src/conformance against the repository's current directories, then inspect the Gradle setup under hello_xr. Reproduce the reported build on Arch Linux and determine which documented path and prerequisites are still valid; done means the Android build instructions match the repository and can be followed successfully.

Written by the indexing model from the issue text.